I don't believe in writer's block. Yes, there are days when you don't want to write, or you can't think of what to write. Still, if your job is to write, you sit down and write. Maybe you write crap. Maybe you can find a nugget in that later. Steven King (not a writer I like very much) writes every day. It's said that George Lucas (who hates writing) locked himself in an office with legal pads and a pencil for eight hours a day, every day for months, until he finished the first draft of A New Hope.

You're right, there really are no rules, except for the one that says WRITE. Everyone's process is different. There are many techniques, many suggestions, many methods. But none of them work unless you write.